A cobpobation



H L. HIRSCHLER Jan. 3l, 1933. .BRAKE oPEnATING uEcHANIsu Re 18,723

l2 Sheets-snelst 1 .Iild Avril '13 1922"' mi? N nA 9. L., a @M M M.

2 sheetssheef. :e

:"Jan.' 31,1933.

HVL HIRSCHLER l BRAKE OPERATING MECHANISM Enea Avril 13. 1922 INVENTOR. fak/7c: L. H//PJc/f/P W @m A TTORNEYS.

original no. amara', am

nonnen L: A

fconraNI, or ombligo, ILLINo nam ernaar The invention relatessto manually or Apedally -operated brake mechanisms, and particularly to brake 'mechanisms on lmotor driven vehicles. f e y -n object. ofthe invention' isi to provldel ai brake mechanism which remains yin adjustment to transmit thema'ximum ener from the brake pedal or'lever to theA bra e band or shoe. y l Y 1Q Another object of the invention is to -provide a brake mechanism ywhich is automatically adjustable to maintain a lixed angular displacement of the pedal or lever to apply `the brakes, regardless of the wear'of the v' brake shoe orbrake lining.

i It is a further object of this' invention to vdevise novel means for compensating for wear on the movable braking element of a hydraulic braking system.`

The invention vpossesses 'other `advantageous features, some of which, with the fore-I oing, will be set forth -at length in the fol- A. owing description Where'y I shall outline in full, that form of the/invention which I have selected for illustration in the drawings accompanying and forming part of the present s ciiication. In'f said drawings I have s own two forms of apparatus embodying ln' linvention, but it isv to be understoodthat do not'limit myself to said forms `since`the invention, as set forth in the claims, may be I embodied in a plurality of otherforms.

i Referring to` said drawings f 'Figure 1 isv a vertical section through a ratus of my invention in its environment. y Figure 2 is a section taken on the line 2 2, Figure 1. l c

Figure 3 is a vertical section through the power applying mechanism associated with the brake operating'lever or pedal. Figure 4 is a side elevation of a mechanically operated brake embodying my 'inven- 45ftion. -l A I i Figure 5 is a section on the line 5--5, Figi ure/4.

' Figure 6 is a section on the line 5 5, Figure 4 looking in the opposite direction; Figure 7 fis a schematic viewvgshowing a Hmsonna, or ASAN raanc'lsco, carbonara,-

a amber a, 19's?, semi ne. staats, meaux-1118,19, reissue` led July 31, 1931. vSerial 10.551,82'1'.

consequently the lever ake drumshowing one Iform of the appa-` ?PTfj-Tf OFFICE assioma :ro .hmmm

Is, a -conroaa'rIoN or rumors 22; Applicatien complete brakingsystemjncorporating this `invention. Y ly The present invention is particularly' applicable to the braking of hea loads, such as motor-trucks. The braking elrlyect is a. function of the coeflicient o f friction of the brake drumiand brakeflining and the` ressure .to

whichtheir'surfaces are subjec Y In operation the brake shoes are movable through suicientdistance to move them from a position of spaced relation with respect to the drum, to tight frictionalfengagement therel with. The arc through which the -brake pedal or .brake lever is movable is limited l and the' forcethat can be applied by the driver to thepedal or lever is limited, and

e between the brake y y pedal or 'lever and the rake shoe actuating element'must be fixed at such ratio as to accomplish the desired movement ofthe brake shoes and their application at the desired pressure, which shoul'dpreferably be a maxi- ,mumatalltimesn Brake linings howeverare subject to'wear, so that the brakes soon. be-

come out Aof adjustment to such an` extent that it is not possible to obtain the maximum braking effect without adjusting the brakes'. f In accordance with my invention means are rlovided for automatically adjusting the y rakes, so thatl the brake lever orlbrake pedal 30 is always operable through `itsarc of maximum effect, to secure maximum braking of the vehicle. Thepull exerted by a levervaries-with the angley of' the lever with lre- Vspect to the line of pull and' an object of the present invention is to maintain thelever in its position of-maximum pull, so' that maxiy vlmum braking/may be accomplished atY all In Figuresl, 2 and 3,1 have lshown the a 'plication of -my invention to a hydraulica y operated brake, the brake shoes being moved1 by the introduction of liquidl under pressure into a c linder associated with/the brake shoes. e liquid 'is laced under pressure by the operation of a p al or lever b the driver, and 1n the accompanying drawings I have shown pedal operated' rakes 'slnee thisl means o operation is very widel employed.

:The initial movement of the pe al serves `to 100 move the brake shoes into contact ,withthe brake drum and requires very little effort, so

piston is a roller which is enga ed -bypa cam 6l on the end of the brake peda 7. The cam is formed with a depression or low face 8 against` which the roller normally rests and with a gradually rising-'face 9 which engages the roller after the initial movement of the pedal. Thus on the initial movement of the pedal the piston is moved a relatively large distance per unit of angular displace-A ment of the pedal and on the further movement lthe piston is moveda rela-tively` short distance per unit of angular 4displacement of the pedal.

The cylinder is charged with liquid and as from the cylinder through a conduit 12, to cylinders 13 associated with therespective brakes. For the purpose'ofl convenience `I shall refer to the cylinder 2) as the primar-y cylinder lor primary motor and the cylinder 13 as the 'secondary cylmder'or secondary motor. Means 'are provided for-equalizing the liquid contents of the cylinders and for compensating for any leakagefrom the'sys- C tem. Formed in the casting of cylinder 2 and above the cylinder chamber, is a liqui containing chamber 14 communicating with the cylinder chamber through aport 15 which is uncovered by the piston at the forf ward end of its stroke. The chamber 14 is provided ywith an open top Asupply tank 16,

arranged above the cylinder.

The 'supply tank is preferably made of .glass or is provided with a transparent side opening, so that the level of the liquid, usually oil, therein ma the operator. A-falling oil level" will indicate a leak in the system and give the eperator an opportunity -to locate and repair the leak before the amount of liquid in the Asystem becomes deficient. s In the present construction, the cylinder 13 is supported on the rear a-xlchousing 17 and disposed within the brake drum 18. f Ar# ranged inthe cylinder 13 are two` pistons 19 between which the liquid under vpressure is introduced to force the pistonsAapart. VThe pistons are normally held in adjacentjrelation by the spring 21 connecting the brake.

l shoes 22. Secured to the ends of the cylinder thepedal is depressed, the liquid is forcedbe readily observed by 13 are bearing members 23 in which sleeves 24A are slidable.' Disposed in the sleeves 24 .are stems 2.5 which are secured to the pistons", 19 and which are provided at their outer ends with heads 26 which engage seats 27 onO the brakeshoes. The hea-d 26 is of greater di- 'amete'r than the Iinterior of the sleeve and abutsmgainst the end of the sleeve when itA fny sleeve, indicated on the drawings by B, is M duce maximum braking effect when there is no lost motion between the piston and the brake shoe due to lining wear. s the brake'- lining 31 wears however, a furthermovement of the piston would be necessary, thus interfering with optimum operation of the lsubstantially equal to the amount of movel 7 ment of the piston which is required to proprimary motor. To overcome this, `means are Y provided for limlting the backward movement of the pistons from the position of maximum. braking, so that at .all times, re-

gardless of the Vwear of the brake lining', the

same distance lof movement ofthe piston is required to produce maximum braking.' Backward movement of the stems 25 and consequentlyl of the pistons' 19 is controlled by the sleeves 24 against the end. of which the heads 26 onthe stemsiabut'.l When the outwardmovement of the pistons totproperly apply the bra-kes is in excessef thev limited' ydistance B, the pistons engage the `innerends of the sleeves and move the sleeves outward. Means are provided" for holding'the sleeves outward, thus changingthe position of the back stop for the/ pistons. AThe sleeves are provided on their periphery with a series of teeth 32, preferably extending around the sleeves, and these teeth are engaged by a toothed pawl 33, which prevents backward movement of the sleeve. The pawl 33 is disposed in a slot in the cylinder head and is pressed against the sleeveiby a spring 34 and operates to prevent'backward movement of the sleeve after it has been advancedby the 'l piston. For the purpose -of 'releasingthe y sleeve when it is desired to reline the brakes brake wear, producesfa chamber of increasing volume between the pistons 19 and liquid for filling this chamber of increasing volume *isv admitted to the system-throu h '-15 in the primary motor when t episton; 3

l Thus: it is apparent that in a completehy'# draulic brak'in apparatus the volumetric ca pacity of the lgi uid system'which' transmits pressureto the rake elements', is'cau'sed 4to automatically increase in ,response to wearl upon one or more braking elements.-

. InFigures 4, 5 and 6, I havefshown 4amechanically operated -brake embodyingmy invention. The brake shoes are expanded or Eessed apart by a, cam or' head 3 6, arranged tween the adjacent ends of the shoes alnd secured to a shaft 37, `as is the usual practice.

Secured tothe shaft 37! is aratchet`wheel-38,j

engaged by a pawl 39 mounted on the ylever 41, which is rotatably mounted on the shaft 37. The-lever 4 1is connected to'theI foot` -pe'dal through theusual brakerods. Rotatably mounted on the .shaft-37. is a ratchet wheel 42,' whichhas a limited rotational movement with respect to the'shaft, this be- -ing accomplished in the present construction by pins 43 on the cam 36vengaged in elongated concentric slots44 in the wheel 42.

.The wheel 42 i is engaged by a. vpavvl 45 mounted on a .fixed pivot. )Rotation of the shaft 37 through the arc of theslots 44 isA suilicient tosecure maximum braking when optimum adjustments prevail. When, due to w'ear of the brake lining, this distance of movement is increased, the .ratchet wheel42 is advanced slightly a'nd'he-ld in its advanced position by the pawl 45. Thus the cam is maintained insuoh adjustment that-rotation of the shaft through a fixed angular distance provides ,maximum braking. When theshaft is held in its advanced position by 40 the pawl 45, thepawl 39 on the lever 41, trips over'` the ratchet wheel38 on the release move` movement of the lever 41, so that the 1ever'4L always' swings through substantiallygthe' same arc, thereby.ma.intaining the leverage with the brake pedal substantially constant.

In Figure 7 there isv shown complete hydraulic brake system incorporating the .devices of Figuresl to 3 inclusive. Thus the braking drums 18 are shown as associated With'wheels 48 of a motor vehicle. Fluid v pipes 49 communicatingwith' the cylinders 13, are connectedlto .pipe 12 which in turn leads from the power applyin mechanism.l

Thismechanisin is suitablymo nted for con-` ,55 venientfope'ration of the pedal or lever 7 I claim:

1. A brake apparatus comprising a brake drum, an element adapted to be moved into frictional engagement with said drum to re- 00 tard the rotation thereof, said vfrictional enagement producing wear which requiresf y urther movementl of the element. during subsequent operations to obtain the same retardinv effect, a lever immediately vconnected to-sai element and operating in its initial gagement produci imoveinent'at low 'leverage ratio to move the element into .contact with the drum and in its therein is 'at the forwar end jof tsstroke.

further movement at high levera e ratio to rum and operative to maintain said low and high leverage ratios for the initial and .further lmovement of the lever.

1 .-.Y 2. AV brake apparatus comprising a brakeI drum, any elemeit adapted to be movedinto Y frictional engagement with said drum to retardthe rotation thereof, said frictional enwear 1 which requires further-movement o ,theelement during subsequent operations to obtain the same retard- 8 ing effect, a lever mediately connectedI toA lsaid element and operating in its initial movement. at low' leverage ratio to movey the element into contact with the drum and in its further movement at high'leverage ratio to 85 press the element against thek drum and automaticallyoperated means intermediate said lever 'and element for maintaining the'initial and braking positions of the lever fixed, so f that l the low andlhigh'leverage ratios are 90 maintained. l

3. A brake vapparatus comprising a brake drum, an element adapted to be movedinto frictional engagement with said drum to retard 'the rotation thereof, said frictio'nal en- 95 gagement producing wear which requires 'further movement of the element during subsequent operations to obtain the same rel ,tarding effect, alever mediately connected to said element and operating in its initial 100 movement at low leverage' ratio to move the elementv into contact with, the drum and in Vits further movement at high leverage ratio to press the element against the drum and means operable onthe' braking movement of 105 theflever for maintaining the release and ,braking positions of vsaid lever substantially fixed.

-4. A brake apparatus comprising a brake drum, an elementadapted to be moved into '.110

frictional engagement with said drumto ref tard the rotation thereof, said frictional engagement producing wear which. requires further movcmentjof the element during subsequent operations toobtain the same retardingefl'ect, 'means .for moving Asaid element into engagement `with the drum, a l spring for effecting release movement of said means, a stop for controlling `the extent of such release movement, means for autom'ati- '12 cally positioning said stop tomaintain the distance'of said release movement substantially constant, a lever for effecting opera tion of said. moving'means and. connections 'Y vbetween said lever and saidmoving means operative to transmit power from the' lever to the moving means/at a low leverage ratio at the initial movement of the lever and at a high ratio for further movement ofthe lever. 5. A brakeapparatus comprising a brake .co cylinder, a lever and means lnterposed be tween the lever and the piston operative to 41'.. i. i I. i fi yu-1l] Il.

'I drum,an elementadapted'to'be moved into frictional engagement with said drum to retard the rotation thereof, said frictionalA engement producin wear `which requires urther movement ol the element'during subsequent operations-to obtain the same retard-` movement of the piston, and means for varying the lposition of the stop to maintain said re ease movement substantially constant.

6. In a friction brake apparatusr an op-l lever movable from release position eratinl y to bra ng posltion, means for causlng the4 initial movement lof the lever to transmit cn-4 at low` leverage and the further movement of the lever to transmit energy athigh leverage and means for compensating. for

. wear whereby said positions remain substantially fixed.

7 In combination with a vehicle provided with a plurality of friction brakes, a secondary liquid motor associated with eachbrake.

.a primary liquid motor connected to said secondary motors, conduits `connecting said primary and secondary motors, a lever for actuating said primary motor` to force liquid through said conduits to the secondary, motors, means associated with each secondary imotor for automatically compensating for wear of said brakes and means compensat-` f Jfing for the nincrease in volume in the system due to the action of sald wear compensating -means,' f

'. 8. In a friction brake apparatus, a movable braking element, hydraulic means' for actuating said element, -said hydraulic means comprising a closed liquid pressure transmitting system, and means for increasing the volumetric capacity of said closed liquid system "inorder'to compensate for wear on said movable braking element.

9.` In a fluid operated friction brake appa'- ratus, a `iuid actuated motor associated with the brake, a cylinder, a conduit connecting the cylinder with the motor, a piston in saidcylinder, a lever for. moving sald iston and means associated with the lever w ereby the initial'movement of the lever causes move- `ment of the piston at a correspondingly higherrate than subsequent movement of the leven 10; In a iuid operated friction brake apparatu's, means forproducing fluid under pressure, comprisinga cylinder, a' piston in said cause an increasing levera 'e on theV piston as 4the lever -1s moved .from

rake release po\. sition to braking position. 1

f logras system, a cy inder, a piston in'said cylinder connected to the brakes,means for automatically compensating for the wear of the brakes, said means servin to increase the initial volume in the cylin er, a secondy cylinder, a conduit connectin said cylinders, a

piston in the second cylin er', 'alever for mov- 1ng',` said second mentioned piston to force liquid' through the conduit -and'means for compensating for the increase in volume in the system due to the action of the compensating means.

l2.' .In a hydraulic operated friction brake system, a' cy inder, a piston in said cylinder connected to the brakes, `means for-automat-l kpiston in the second cylinder, a lever for movmgr said second lmentioned piston to force liquid through the conduit and means in the second cylinder causing the introduction of r liquid .into the system to compensate for the the action of Y increase in -volume caused by the compensatmg means.

a brake shoe, alining therefor, Huid ressure means positionedwithin said drum or forcing said lining into engagement with said drum, a stop for limiting the retractile movement'of said. shoe and'said means,r a take-up associated'with said sto and means for automatically adjusting sai take-up so as to permita substantially equal retractile movement of said forcing means regardless of the condition Vof wear of saidlining.:

'14. In braking mechanism, a wear member, astem, means positione within .the drum formoving said stem longitudinally for forcing said wear member into engagement with said drum, a stop for limiting the retractile movement of said stem, a ta e-up associated with said stem and means for automatically adjustingsaid take-up .so as to permit a substantially equal retractile movement of said stem regardless of the condition of said wear member.

brake drum,a brake shoe, a lining therefor, a stem for forcing said lining into engagement with said drum, a cylinder, a piston within said cylinder for operating said stem, a takeup associated with said stem, and means for automatically adjusting vsaid Itake-up so as to permit a lsubstantially .l equal yretra'ctile lmovement of said stem regardless of the condition of wear of said lining.

416. In a friction brake apparatus, a movable braking actuating said element, said hydraulic means comprising a closed liquid .pressure transmitting system, and means for automatically increasing thel volumetric capacity of l said a brake drinni f 15'. In braking mechanisml for vehicles, a-

element, hydraulic 'means' for,

11.. a hydraulic operated friction brake 13. In braking mechanism, a brake drum,

1 away from the drum will be substantially the closed liquidsystem in order .to compensate for wear on said movable braking element.

17 Inbrakin mechanism tively movable riction me bers adapted to be forced intoengagement with one another for braking purposes, a hydraulically operated member for creating pressure between l 'said relatively movable members, means for creating hydraulic pressure for operating said member, means for automatically replenishing said hydraulic pressure creating means with fluid, a stop for limiting the sepathe drum for braking purposes, an operating member for creating pressure between said relatively movable friction members located therebetween, a stop for Vlimiting the separationL of said friction `members from said drum and an automatic take-up cooperating with said stop to compensate for wear of the -braking members so that their movement same after wear has occurred between them as `in their initial position, said stop and take-up positioned between the movable members and being associated with said operating member.

` 219. In braking mechanism, a drum, a air l Wear member, a Vstem for forcmg said wear of relatively movable friction mem ers adapted to be forced into engagement` with the drum'for braking purposes, an operatinn member for creating pressure between said relatively-movable friction members and located therebetween, a stop for limiting the Irelease movement of said friction members and an automaticA take-up cooperating with said stop toc ompensate for wear of the braking members so that-their movement away from the drum will be substantially the same after wear has occurred between them asin their initial position, said stop and take-up being located between said operating member, and said movable friction members.

20. In braking mechanism a pair of rela- A:tively movable friction mem ers adapted to be forced into engagement with one another for braking purposes, an operatin member for creating pressure between sai relatively movable members, an adjustable take-up immovable during the non-adjustingrstrokes (5f-the operating memberfor limiting the separation of said members, and means cooperating with said 4stop fori-mowing said stopwhen desirable to compensate for wear between the pair of braking members so that their lrelative movement away from one an- `other -will be substantially the same after a pair of relaalso interposed between said friction members for limiting the separation of said members from said drum, and an automatic takeup also interposed between said friction members and co-operating with said stops to move the normal position of ,said stops and of portions. of said operating members outward to compensate for wear of the pair of braking members so tthat their relative movement away from the drum will be substantially the same after wear has occurred between .them as intheir initial condition.

22. In braking mechanism, a brakedrum,

a brake shoe, a lining therefor, hydraulic means for forcing said lining into engagement with said drum, a stop for limitin the'retractile movement ofsaid shoe and sai means, atake-up associated with Vsaid stop, and means for automatically adjusting said take-up soas to permit a substantially equal.

retractile movement of said forcing eans regardless of the condition of wear o said 1in1ng,.said hydraulic means including a device for creating hydraulic pressure, and means for automatically replenishing said device.

23, In braking mechanism, a brake drum, a

member into engagement with said drum, an

.adjustable stop held immovable during nona'djustinl strokes of the operating member,

vfor limitm the retractile movement of said stem, a ta e-up associated with said stem and means for automatically adjusting said stop so as -to permlta substantially equal retractile movement of said stem regardless of the conditionof said wear member;

24. In braking mechanism, a brake drum, a wear member, a stemfor forcing said wear member into engagement with said drum, h draulic means for moving said. stem 10ng1tudina1ly,a stop for limiting the retractile plenishing the fluid' in said pressure creatin device. f

n testimony whereof, I have hereunto signed my name.

' HORACE L. HIRSCHLER. 

